Glutathione depletion and disruption of intracellular ionic homeostasis regulate lymphoid cell apoptosis.
Intracellular glutathione (GSH) depletion is an important hallmark of apoptosis. We have recently shown that GSH depletion by its extrusion regulates apoptosis independently of excessive reactive oxygen species accumulation. However, the mechanisms by which GSH depletion regulates apoptosis are still unclear. Because disruption of intracellular ionic homeostasis, associated with apoptotic volume decrease (AVD), is necessary for the progression of apoptotic cell death, we sought to evaluate the relationship between GSH transport and ionic homeostasis during Fas ligand (FasL)-induced apoptosis in Jurkat cells. GSH depletion in response to FasL was paralleled by distinct degrees of AVD identified by differences in cellular forward scatter and electronic impedance analysis. Inhibition of GSH efflux prevented AVD, K+ loss, and the activation of two distinct ionic conductances, mediated by Kv1.3 and outward rectifying Cl- channels. Reciprocally, stimulation of GSH loss accelerated the loss of K+, AVD, and consequently the progression of the execution phase of apoptosis. Although high extracellular K+ inhibited FasL-induced apoptosis, GSH depletion was largely independent of K+ loss. These results suggest that deregulation of GSH and ionic homeostasis converge in the regulation of apoptosis in lymphoid cells.
Franco
Rodrigo
R
Laboratory of Signal Transduction, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
DeHaven
Wayne I
WI
Sifre
Maria I
MI
Bortner
Carl D
CD
Cidlowski
John A
JA
D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002469:Cell Separation; D053222:Fas Ligand Protein; D005434:Flow Cytometry; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D007477:Ions; D019169:Jurkat Cells; D008055:Lipids / Q000737:chemistry; D008214:Lymphocytes / Q000378:metabolism* / Q000473:pathology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011188:Potassium / Q000737:chemistry / Q000378:metabolism; D051670:Shaw Potassium Channels / Q000378:metabolism
D053222:Fas Ligand Protein; D007477:Ions; D008055:Lipids; D051670:Shaw Potassium Channels; D011065:Poly(ADP-ribose) Polymerases; D053148:Caspase 3; D005978:Glutathione; D011188:Potassium